Billard Marie-Noëlle, De Serres Gaston, Gariépy Marie-Claude, Boulianne Nicole, Toth Eveline, Landry Monique, Skowronski Danuta M
Centre de recherche du CHU de Québec-Université Laval, Quebec City, QC, Canada.
Institut national de santé publique du Québec, Quebec City, QC, Canada.
PLoS One. 2017 Oct 11;12(10):e0186070. doi: 10.1371/journal.pone.0186070. eCollection 2017.
A large measles outbreak occurred in Quebec, Canada, in 2011. Although nearly two-thirds of the cases occurred in only two health districts, a mass vaccination campaign targeting all Quebec elementary and high school students without valid two-dose history was undertaken to prevent future outbreaks. We compared rates of non-vaccination and age at first measles vaccine dose among students in the two most-affected districts and the rest of the province and estimated the improvement in overall student measles immunity due to the mass school-based vaccination campaign.
Data were extracted from the provincial vaccination registry for students in kindergarten to grade 11 during the 2011/2012 school year. A telephone survey was conducted in three sub-groups: students whose first measles vaccine dose recorded in the vaccination registry was received during the 2011 school vaccination campaign; students with no dose recorded in the registry whose parents refused receipt during the school campaign; and students with no dose recorded in the registry and no information about parental consent/refusal during the school campaign.
Neither the prevalence of being non-vaccinated nor a younger age at first pediatric dose were higher in the two most-affected districts versus the rest of the province. The school campaign vaccinated nearly 8% of all students including 7% who previously received at least one dose. Before the outbreak, 3% of students were not vaccinated and one-third of these (1%/3%) were vaccinated during the campaign. The campaign likely increased the absolute school population immunity by just 1.7%.
The concentration of measles cases in the two most-affected health districts during the large Quebec outbreak is not explained by more students who were unvaccinated or who had received their first vaccine dose at a younger age. The vaccination campaign reached one-third of unvaccinated students and only marginally improved population immunity.
2011年加拿大魁北克省发生了大规模麻疹疫情。尽管近三分之二的病例仅发生在两个卫生区，但仍开展了一项针对所有无有效两剂接种史的魁北克中小学生的大规模疫苗接种运动，以预防未来的疫情爆发。我们比较了受影响最严重的两个区和该省其他地区学生的未接种率及首次接种麻疹疫苗的年龄，并估计了基于学校的大规模疫苗接种运动对学生整体麻疹免疫力的提升情况。
从省级疫苗接种登记处提取了2011/2012学年幼儿园至11年级学生的数据。对三个亚组进行了电话调查：在疫苗接种登记处记录的首次麻疹疫苗接种是在2011年学校疫苗接种运动期间进行的学生；登记处未记录接种情况且其父母在学校运动期间拒绝接种的学生；登记处未记录接种情况且在学校运动期间没有父母同意/拒绝信息的学生。
与该省其他地区相比，受影响最严重的两个区的未接种率和首次小儿剂量接种年龄均不更高。学校运动为所有学生中的近8%接种了疫苗，其中包括7%之前至少接种过一剂的学生。在疫情爆发前，3%的学生未接种疫苗，其中三分之一（1%/3%）在运动期间接种了疫苗。该运动可能仅使学校人口的绝对免疫力提高了1.7%。
魁北克大规模疫情期间受影响最严重的两个卫生区麻疹病例的集中情况，并非由更多未接种疫苗或首次接种疫苗年龄更小的学生所导致。疫苗接种运动覆盖了三分之一未接种疫苗的学生，仅略微提高了人群免疫力。
